Methods and apparatus for battery current monitoring

ABSTRACT

Methods and apparatus are disclosed for battery current monitoring. An example apparatus includes a haptic device, an isolation switch to deliver power from a battery to the haptic device, an integrator to integrate a signal based on a current from the battery to the haptic device to generate an integrator output, and control logic to control the isolation switch based on a comparison of the integrator output to a threshold.

RELATED APPLICATION

This patent arises from a continuation of U.S. patent application Ser.No. 15/587,111, (now U.S. Pat. No. 10,707,672) which was filed on May 4,2017. U.S. patent application Ser. No. 15/587,111 is hereby incorporatedherein by reference in its entirety. Priority to U.S. patent applicationSer. No. 15/587,111 is hereby claimed.

FIELD OF THE DISCLOSURE

This disclosure relates to monitoring, and in particular, to methods andapparatus for battery current monitoring.

BACKGROUND

Wearable devices such as wrist wearable computing devices and headwearable devices (e.g., virtual reality headsets) can provideenhancements to user experiences in new ways. For example, virtualreality headsets can provide for user interaction, as part of thoseexperiences. In particular, head mounted displays can be a convenientway for users to gain access to these new experiences. Similarly, wristwearable computing devices can provide users with convenient access toexperiences and/or information. However, some improvements may beneeded, since wearable devices such as wrist wearable devices, headwearable devices and/or the like can come in close contact with users.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of an example system for battery currentmonitoring in a wearable device.

FIG. 2 is a timing diagram illustrating operation of the example batterycurrent monitoring system in the wearable device shown in FIG. 1 .

FIGS. 3-5 are a flowchart representative of example of machine readableinstructions which may be executed to implement the example system forbattery current monitoring in the wearable device of FIGS. 1 and 2 .

FIG. 6 is a block diagram of an example processing platform capable ofexecuting the example machine-readable instructions of the flowchart ofFIGS. 3-5 to implement the example system for battery current monitoringin the wearable device of FIGS. 1 and 2 .

DETAILED DESCRIPTION

FIG. 1 is a circuit diagram of an example system 100 constructed inaccordance with teachings of this disclosure for battery currentmonitoring in a battery operated wearable device 102. The batteryoperated wearable device 102 can include a light emitting diode (LED)104A and a light emitting diode (LED) controller 104B coupled with theLED 104A to control operation of the LED 104A. The battery operatedwearable device 102 can also include a haptic device 106A (e.g., avibrator 106A) and a haptic device controller 106B (e.g., a vibratorcontroller 106) coupled with the haptic device 106A (e.g., vibrator106A) to control operation of the haptic device 106A (e.g. controloperation of the vibrator 106A.) The battery operated wearable device102 can also include a processor. The processor of the battery operatedwearable device 102 can include an interrupt to save system state of thebattery operated wearable device 102. The battery operated wearabledevice 102 can also include additional components not shown in FIG. 1 .

The example system 100 can include a battery 108 and a currentcontroller apparatus (e.g., current controller 110) to prevent injuryfrom the battery operated wearable device 102. Such wearable device canbe a wrist wearable device or a head wearable device. As mentionedpreviously, wearable devices such as wrist wearable devices, headwearable devices and/or the like can come in close contact with users.As a head wearable system, the example system 100 can avoid thermalinjury damage due to overcurrent. As a wrist wearable system, theexample system can avoid thermal wrist injury due to overcurrent.

As shown in the example of FIG. 1 , example current controller 110 caninclude example battery couplers 112A, 112B, example sense resistor 114,example current sense amplifier 116, example integrator 118, examplecomparator 120, example control logic 122 and example isolation switch124. The battery couplers 112A, 112B can couple current of the battery108, for example, into battery operated wearable device 102. The senseresistor 114 can be in circuit with the battery couplers 112A, 112B togenerate a voltage from the current of the battery 108. The currentsense amplifier 116 can sense the voltage of the sense resistor atdifferential inputs 116A, 116B of the current sense amplifier 116. Theintegrator 118 can be in circuit with an output 116C of the currentsense amplifier to integrate the output 116C of the current senseamplifier 116 and to generate an integrator output 118A.

The control logic 122 can generate an overcurrent threshold reference122A. The comparator 120 can compare the overcurrent threshold reference122A and the integrator output 118A to generate an overcurrent indicator120A. For example, the comparator 120 can determine whether theintegrator output 118A satisfies the overcurrent threshold reference122A. For example, the comparator 120 can determine that the integratoroutput 118A satisfies the overcurrent threshold reference 122A when theintegrator output 118A at least meets or exceeds the overcurrentthreshold reference 122A. When the comparator 120 determines that theintegrator output 118A satisfies the overcurrent threshold reference122A, the comparator 120 can generate the overcurrent indicator 120A totrigger an overcurrent fault status. For example, a low to hightransition can be generated for the overcurrent indicator, when thecomparator 120 determines that the integrator output 118A satisfies theovercurrent threshold reference 122A, so as to trigger the overcurrentfault status.

The control logic 122 can generate an isolation switch control signal122B in response to the overcurrent indicator 120A. For example, thecontrol logic 122 can generate the isolation switch control signal 122Bin response to the overcurrent fault status of the overcurrent indicator120A. The isolation switch 124 can interrupt delivery of the current ofthe battery 108 to a load (e.g., LED 104A, e.g., haptic device 106A) inresponse to the isolation switch control signal 122B to prevent burninjury to a wearer of the battery operated wearable device 102. Theisolation switch 124 can include an isolation field effect transistor(FET) 124, as shown in the example of FIG. 1 .

The control logic 122 can also generate an integrator reset controlsignal 122C. The integrator reset control signal 122C can be periodic,to reset the integrator on a periodic basis. The integrator 118 caninclude an integrator reset switch 126, to reset the integrator (e.g.,periodically) in response to the (e.g., periodic) integrator resetcontrol signal 122C. For example, the comparator 120 can determine thatthe integrator output 118A does not satisfy the overcurrent thresholdreference 122A, when the integrator output 118A does not at least meetor exceed the overcurrent threshold reference 122A. When the comparator120 determines that the integrator output 118A does not satisfy theovercurrent threshold reference 122A, the comparator 120 does nottrigger the overcurrent fault status for the overcurrent indicator 120A.For example, when the comparator 120 determines that the integratoroutput 118A does not satisfy the overcurrent threshold reference 122A,the comparator 120 does not generate the low to high transition for theovercurrent indicator 120A.

The control logic 122 can monitor for the overcurrent indicator 120A fortriggering the overcurrent fault status. When the integrator output 118does not satisfy the overcurrent threshold reference 122A, and thecomparator 120 does not trigger the overcurrent fault status for theovercurrent indicator 120A, based on its monitoring of the overcurrentindicator 120A, the control logic 122 can generate the integrator resetcontrol signal 122C.

The control logic 122 can also generate a save system state controlsignal 128 in response to the overcurrent fault status of theovercurrent indicator 120A. For example, when there is an overcurrentfault, the control logic 122 can respond by generating the save systemstate control signal 128 The processor of the battery operated wearabledevice 102 can include the interrupt to save system state of the batteryoperated wearable device 102. The interrupt can be processed by theprocessor to save system state of the battery operated wearable device102 in response to the save system state control signal 128. A delayperiod of time (e.g., 500 milliseconds) can provide the processor withsufficient time to save system state of the battery operated wearabledevice 102 in non-volatile memory, in response to the save system statecontrol signal 128. This delay period of time can be designated as asave system state period of time. For example, prior to interruptingdelivery of the current of the battery to the processor, the delayperiod (e.g., 500 milliseconds) can provide the processor withsufficient time to save system state of the battery operated wearabledevice 102. For example, a delay of the delay period (e.g., 500milliseconds) can pass between a first time when the overcurrentindicator 120A indicates an overcurrent of the battery current and asecond time when the isolation switch control signal 122B is to activatethe isolation switch 124 to interrupt delivery of the current of thebattery to the load (e.g., the processor in addition to othercomponents, e.g., LED 104A, e.g., haptic device 106A.) Prior to beingactivated, the inactivated isolation switch 124 can be in a conductingstate, so as to conduct the battery current. However, upon beingactivated, the isolation switch 124 can be in a non-conducting state, soas to interrupt the battery current. The control logic can include adelay timer 130 to generate the delay of the delay period of time (e.g.,the delay of the save system state period of time.) For example, thedelay timer 130 can generate the delay of the delay period (e.g., 500milliseconds) to enable the processor to save system state of thebattery operated wearable device 102 in non-volatile memory, prior tothe isolation switch 124 interrupting delivery of the current of thebattery. Of interest, the system of FIG. 1 can prevent thermal injurywithout the use of a temperature sensor, thermistor or the like. Assuch, it may reduce costs and part counts relative to temperaturesensing devices, and is not susceptible to defects associated withfailure of such temperature sensing equipment.

Of further interest are possible advantages of the circuitry used toimplement the components of FIG. 1 (e.g., the example LED controller104B, example haptic device controller 106B, example integrator 118,example comparator 120, example control logic 122, example integratorreset switch 126 and example delay timer 130), relative to alternativeimplementations using software or firmware executing on a processor. Forexample, relative to alternative implementations using software orfirmware executing on a processor, circuitry used to implement thecomponents of FIG. 1 may provide for more modular design, may providefor greater reliability, may consume less power and/or may providegreater performance in protecting against thermal injury, which mayotherwise be caused by the overcurrent event.

FIG. 2 is a timing diagram illustrating operation of the example batterycurrent monitoring system in the wearable device shown in FIG. 1 . Theexample of FIG. 2 shows a battery current trace 202, an overcurrentthreshold reference 204, an integrator output trace 206 and anovercurrent indicator trace 208, all relative to the same time axis 210.

The battery current trace 202 shows battery current varying over time,relative to the time axis 210, within safe limits prior to a malfunctionportion 202A of the current trace 202. The malfunction portion 202A ofthe current trace 202 representatively illustrates occurrence of amalfunction in the wearable device, in which battery current increasesto a dangerous level (i.e. an overcurrent situation that could generateheat, which may lead to injury without intervention.)

The integrator output trace 206 is indicative of charge consumed by thewearable device from the battery current. The integrator can include thereset switch as discussed previously herein, to reset the integrator(e.g., periodically) in response to the (e.g., periodic) integratorreset control signal. As shown in the example of FIG. 2 , for theintegrator output trace 206, one example cycle period T extends betweenconsecutive resets of the integrator. Accordingly, after a reset occursat the beginning of example cycle period T, the integrator output trace206 is shown in FIG. 2 as ramping up until dropping when a subsequentreset occurs at the end of example cycle period T. In the example ofFIG. 2 , one example period of charge consumed represents averagebattery current, when the output of the integrator can be compared withthe overcurrent threshold reference 204.

In response to occurrence of the malfunction in the wearable device(representatively illustrated by malfunction portion 202A of the currenttrace 202), FIG. 2 shows a point 206A, when the integrator output trace206 crosses and/or exceeds the overcurrent threshold reference 204. Theexample of FIG. 2 shows a low to high transition 208A in the overcurrentindicator trace 208, in response to the integrator output trace 206crossing and/or exceeding the overcurrent threshold reference 204. Thisrepresentatively illustrates charge consumed by the wearable device fromthe battery current increasing above the overcurrent threshold, andtriggering an overcurrent fault status. This can prompt the system toisolate the battery from the system. For example, the isolation switchcontrol signal can be generated in response to the low to hightransition 208A in the overcurrent trace 208. As discussed previouslyherein, the isolation switch 124 can interrupt delivery of the currentof the battery to the load in response to the isolation switch controlsignal, so as to prevent burn injury to a wearer of the battery operatedwearable device.

While example manners of implementing and using the example system 100for battery current monitoring in the battery operated wearable device102 of FIGS. 1 and 2 are illustrated in FIGS. 1 and 2 , one or more ofthe elements, processes and/or devices illustrated in FIGS. 1 and 2 maybe combined, divided, re-arranged, omitted, eliminated, and/orimplemented in any other way. Further, the example system 100 forbattery current monitoring, example battery operated wearable device102, example LED controller 104B, example haptic device controller 106B,example current controller 110, example integrator 118, exampleintegrator output 118A, example comparator 120, example overcurrentindicator 120A, example control logic 122, example overcurrent thresholdreference 122A, example isolation switch control signal 122B, exampleintegrator reset control signal 122C, example isolation switch 124,example integrator reset switch 126 and example save system statecontrol signal 128 may be implemented by hardware, software, firmwareand/or any combination of hardware, software and/or firmware.

Thus, for example, any of the example system 100 for battery currentmonitoring, example battery operated wearable device 102, example LEDcontroller 104B, example haptic device controller 106B, example currentcontroller 110, example integrator 118, example integrator output 118A,example comparator 120, example overcurrent indicator 120A, examplecontrol logic 122, example overcurrent threshold reference 122A, exampleisolation switch control signal 122B, example integrator reset controlsignal 122C, example isolation switch 124, example integrator resetswitch 126 and example save system state control signal 128 could beimplemented by one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). When reading any of theapparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example system 100for battery current monitoring, example battery operated wearable device102, example LED controller 104B, example haptic device controller 106B,example current controller 110, example integrator 118, exampleintegrator output 118A, example comparator 120, example overcurrentindicator 120A, example control logic 122, example overcurrent thresholdreference 122A, example isolation switch control signal 122B, exampleintegrator reset control signal 122C, example integrator reset switch126 and example save system state control signal 128 is/are herebyexpressly defined to include a tangible computer readable storage deviceor storage disk such as a memory, a digital versatile disk (DVD), acompact disk (CD), a Blu-ray disk, etc. storing the software and/orfirmware. Further still, example system 100 for battery currentmonitoring, example battery operated wearable device 102, example LED104A, example LED controller 104B, example haptic device 106A, examplehaptic device controller 106B, example battery 108, example currentcontroller 110, example battery couplers 112A, 112B, example senseresistor 114, example current sense amplifier 116, example differentialinputs 116A, 116B of the current sense amplifier 116, example output116C of the current sense amplifier, example integrator 118, exampleintegrator output 118A, example comparator 120, example overcurrentindicator 120A, example control logic 122, example overcurrent thresholdreference 122A, example isolation switch control signal 122B, exampleintegrator reset control signal 122C, example isolation switch 124,example integrator reset switch 126 and example save system statecontrol signal 128 may include more than one of any or all of theillustrated elements, processes and devices.

FIGS. 3-5 are a flowchart representative of example machine readableinstructions which may be executed to implement the example system forbattery current monitoring in the wearable device of FIGS. 1 and 2 . Inthis example, the machine readable instructions correspond to a programfor execution by a processor such as the processor 612 shown in theexample processor platform 600 discussed below in connection with FIG. 6. The program may be embodied in software stored on a non-transitorycomputer readable medium and/or a tangible computer readable storagemedium such as a CD-ROM, a floppy disk, a hard drive, a digitalversatile disk (DVD), a Blu-ray disk, or a memory associated with theprocessor 612, but the entire program and/or parts thereof couldalternatively be executed by a device other than the processor 612and/or embodied in firmware or dedicated hardware. Further, although theexample program is described with reference to the flowchart illustratedin FIGS. 3-5 , many other methods of the example system for batterycurrent monitoring in the wearable device may alternatively be used. Forexample, the order of execution of the blocks may be changed, and/orsome of the blocks described may be changed, eliminated, or combined.

The method 300 to prevent thermal injury in a wearable device shown inthe example of FIGS. 3-5 begins at block 302. At block 302, current froma battery can be sensed. For example, as shown in the example of FIG. 1, the battery couplers 112A, 112B can couple current of the battery 108,for example, into battery operated wearable device 102. The senseresistor 114 can be in circuit with the battery couplers 112A, 112B togenerate a voltage from the current of the battery 108. The currentsense amplifier 116 can sense the voltage of the sense resistor atdifferential inputs 116A, 116B of the current sense amplifier 116.

Next, at block 304 of the example of FIG. 3 , a signal representative ofthe current from the battery can be integrated using an integrator togenerate an integrator output. For example, as shown in the example ofFIG. 1 , the integrator 118 can be in circuit with an output 116C of thecurrent sense amplifier to integrate the output 116C of the currentsense amplifier 116 and to generate an integrator output 118A.

Next, at block 306 of the example of FIG. 3 , the integrator output andan overcurrent threshold reference can be compared. For example, asshown in the example of FIG. 1 , the comparator 120 can compare theovercurrent threshold reference 122A and the integrator output 118A. Forexample, the comparator 120 can determine whether the integrator output118A satisfies the overcurrent threshold reference 122A.

Next, at decision block 308 of the example of FIG. 3 , it is determinedwhether the integrator output satisfies the overcurrent thresholdreference. For example, if it is determined that the integrator outputdoes not satisfy the overcurrent threshold reference, then at block 310the integrator can be reset, and flow of execution of method 300 can betransferred to block 302. For example, if it is determined that theintegrator output does not satisfy the overcurrent threshold reference,monitoring can continue, then at block 310 the integrator can be resetbased on a periodic signal, which can be generated by the control logic.For example, as shown in the example of FIG. 1 , the comparator 120 candetermine that the integrator output 118A does not satisfy theovercurrent threshold reference 122A, when the integrator output 118Adoes not at least meet or exceed the overcurrent threshold reference122A. When the comparator 120 determines that the integrator output 118Adoes not satisfy the overcurrent threshold reference 122A, thecomparator 120 does not trigger an overcurrent fault status for theovercurrent indicator 120A. For example, when the comparator 120determines that the integrator output 118A does not satisfy theovercurrent threshold reference 122A, the comparator 120 does notgenerate the low to high transition for the overcurrent indicator 120A.

The control logic 122 can monitor for the overcurrent indicator 120A fortriggering of the overcurrent fault status. When the integrator output118 does not satisfy the overcurrent threshold reference 122A, and thecomparator 120 does not trigger the overcurrent fault status for theovercurrent indicator 120A, based on its monitoring of the overcurrentindicator 120A, the control logic 122 can generate the integrator resetcontrol signal 122C. The integrator reset control signal 122C can beperiodic, to reset the integrator on a periodic basis. The integrator118 can include an integrator reset switch 126, to reset the integrator(e.g., periodically) in response to the (e.g., periodic) integratorreset control signal 122C.

In the example of FIG. 3 , at decision block 308, if it is determinedthat the integrator output does satisfy the overcurrent thresholdreference, then flow of execution of method 300 can continue to block312. At block 312 the overcurrent indicator can be generated. Forexample, when the integrator output satisfies the overcurrent thresholdreference, the overcurrent indicator can be generated to trigger theovercurrent fault status. For example, as shown in the example of FIG. 1, the comparator 120 can compare the overcurrent threshold reference122A and the integrator output 118A to generate the overcurrentindicator 120A. For example, the comparator 120 can determine whetherthe integrator output 118A satisfies the overcurrent threshold reference122A. For example, the comparator 120 can determine that the integratoroutput 118A satisfies the overcurrent threshold reference 122A when theintegrator output 118A at least meets or exceeds the overcurrentthreshold reference 122A. When the comparator 120 determines that theintegrator output 118A satisfies the overcurrent threshold reference122A, the comparator 120 can generate the overcurrent indicator 120A totrigger the overcurrent fault status. For example, the low to hightransition can be generated for the overcurrent indicator, when thecomparator 120 determines that the integrator output 118A satisfies theovercurrent threshold reference 122A, so as to trigger the overcurrentfault status.

Next, at block 314 in the example of FIG. 3 , a save system statecontrol signal can be generated in response to the overcurrentindicator. For example, when the overcurrent indicator triggers theovercurrent fault status, the system state control signal can begenerated in response. For example, as shown in the example of FIG. 1 ,the control logic 122 can generate the save system state control signal128 in response to the overcurrent fault status of the overcurrentindicator 120A. For example, when there is an overcurrent fault, thecontrol logic 122 can respond by generating the save system statecontrol signal 128 The processor of the battery operated wearable device102 can include the interrupt to save system state of the batteryoperated wearable device 102. The interrupt can be processed by theprocessor to save system state of the battery operated wearable device102 in response to the save system state control signal 128.

Next, at block 316 in the example of FIG. 4 , a delay can be started forsaving system state. At block 318 there can be a delay for a save systemstate period of time after generating the save system state controlsignal. At decision block 320 it can be determined when the delaying forthe save system state period of time is finished. If it is determinedthat the delaying for the save system state period of time is notfinished, then flow of execution of method 300 can be transferred toblock 318 for delay. However, if it is determined that the delaying forthe save system state period of time is finished, then flow of executionof method 300 can continue to block 322 to generate the isolation switchcontrol signal.

For example, as shown in the example of FIG. 1 , a delay period of time(e.g., 500 milliseconds) can provide the processor with sufficient timeto save system state of the battery operated wearable device 102 innon-volatile memory, in response to the save system state control signal128. This delay period of time can be designated as the save systemstate period of time. For example, prior to interrupting delivery of thecurrent of the battery to the processor, the delay period (e.g., 500milliseconds) can provide the processor with sufficient time to savesystem state of the battery operated wearable device 102. For example, adelay of the delay period (e.g., 500 milliseconds) can pass between afirst time when the overcurrent indicator 120A indicates an overcurrentof the battery current and a second time when the isolation switchcontrol signal 122B is to activate the isolation switch 124 to interruptdelivery of the current of the battery to the load (e.g., the processorin addition to other components, e.g., LED 104A, e.g., haptic device106A.) The control logic can include a delay timer 130 to generate thedelay of the delay period of time (e.g., the delay of the save systemstate period of time.) For example, the delay timer 130 can generate thedelay of the delay period (e.g., 500 milliseconds) to provide theprocessor with sufficient time to save system state of the batteryoperated wearable device 102 in non-volatile memory, prior to theisolation switch 124 interrupting delivery of the current of thebattery.

Next, at block 322 in the example of FIG. 4 , the isolation switchcontrol signal can be generated. For example, the isolation switchcontrol signal can be generated in response to the overcurrent indicator(e.g., in response to the overcurrent fault status of the overcurrentindicator.) For example, the isolation switch control signal can begenerated in response to the overcurrent indicator after delaying forthe save system state period of time. Next at block 324, the isolationswitch can be activated to interrupt the battery current in response tothe isolation switch control signal. Next at block 326, LED current fromthe battery can be interrupted. Next at block 328, haptic device currentfrom the battery can be interrupted.

For example, as shown in the example of FIG. 1 , the control logic 122can generate the isolation switch control signal 122B in response to theovercurrent indicator 120A. For example, the control logic 122 cangenerate the isolation switch control signal 122B in response to theovercurrent fault status of the overcurrent indicator 120A. Theisolation switch 124 can be activated interrupt delivery of the currentof the battery 108 to the load (e.g., LED 104A, e.g., haptic device106A) in response to the isolation switch control signal 122B to preventburn injury to a wearer of the battery operated wearable device 102.Prior to being activated, the inactivated isolation switch 124 can be ina conducting state, so as to conduct the battery current. However, uponbeing activated, the isolation switch 124 can be in a non-conductingstate, so as to interrupt the battery current. The isolation switch 124can include an isolation field effect transistor (FET) 124, as shown inthe example of FIG. 1 .

Next, at block 330 in the example of FIG. 5 , a delay can be started fora cool down period of time, after interrupting the battery current. Atblock 332 there can be a delay for a cool down period of time afterinterrupting the battery current. For example, after the overcurrentfault of the battery operated wearable device, and after theinterrupting of battery current, a cool down period of time can let thebattery operated wearable device cool down from a first temperature(e.g., higher temperature) associated with the overcurrent fault to asecond temperature that is lower than the first temperature. At decisionblock 334 it can be determined when the delaying for the cool downperiod of time is finished. If it is determined that the delaying forthe cool down period of time is not finished, then flow of execution ofmethod 300 can be transferred to block 332 for delay. However, if it isdetermined that the delaying for the cool down period of time isfinished, then flow of execution of method 300 can continue to block 336to generate reset the isolation switch. For example, delay timer 130 ofcontrol logic 122 shown in the example of FIG. 1 can be used to startthe cool down period of time, after interrupting the battery current,and to determine when the cool down period of time is finished.

Next, at block 336 in the example of FIG. 5 , the isolation switch canbe reset. At block 338, battery current can be reactivated (e.g.,current from the battery can once again be conducted for operation ofthe battery operated device.) For example, while the isolation switchwas activated, the isolation switch could be in the non-conductingstate, so as to interrupt the battery current. However, upon theisolation switch being reset, the isolation switch can be inactivated.Upon being reset, the inactivated isolation switch 124 can be in theconducting state, so as to conduct the battery current once again. Forexample, after the delay timer 130 of control logic 122 determines thatthe cool down period of time is finished, control logic 122 shown in theexample of FIG. 1 can use the isolation switch control signal 122B toreset the isolation switch 124 (e.g., to inactivate the isolation switch124 so as to be in the conducting state once again.)

Next, at decision block 340 in the example of FIG. 5 , it is determinedwhether to end the cycle of preventing thermal injury in the wearabledevice. For example, if a control input registered at a time determinesthat the cycle is not to end at that time, then flow execution transfersto block 302 shown in FIG. 3 . However, if a control input registered atthat time determines that the cycle is to end at that time, then afterblock 340, the method 300 to prevent thermal injury in the wearabledevice can end.

As mentioned above, the example processes of FIGS. 3-5 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a tangible computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory(ROM), a compact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and to exclude transmission media. Asused herein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. Additionallyor alternatively, the example processes of FIGS. 3-5 may be implementedusing coded instructions (e.g., computer and/or machine readableinstructions) stored on a non-transitory computer and/or machinereadable medium such as a hard disk drive, a flash memory, a read-onlymemory, a compact disk, a digital versatile disk, a cache, arandom-access memory and/or any other storage device or storage disk inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, for brief instances, for temporarily buffering,and/or for caching of the information). As used herein, the termnon-transitory computer readable medium is expressly defined to includeany type of computer readable storage device and/or storage disk and toexclude propagating signals and to exclude transmission media. As usedherein, when the phrase “at least” is used as the transition term in apreamble of a claim, it is open-ended in the same manner as the term“comprising” is open ended.

FIG. 6 is a block diagram of an example processing platform capable ofexecuting the example machine-readable instructions of the flowchart ofFIGS. 3-5 to implement the example system for battery current monitoringin the wearable device of FIGS. 1 and 2 . The processor platform 600 canbe implemented in a wearable (e.g., wrist wearable or head wearable)device. Alternatively or additionally, processor platform 600 can be canbe, for example, a personal computer, a mobile device (e.g., a cellphone, a smart phone, a tablet such as an iPad™), a personal digitalassistant (PDA), an Internet appliance, a DVD player, a CD player, aBlu-ray player, a gaming console, a personal video recorder, or anyother type of computing device.

The processor platform 600 of the illustrated example includes aprocessor 612. The processor 612 of the illustrated example is hardware.For example, the processor 612 can be implemented by one or moreintegrated circuits, logic circuits, microprocessors or controllers fromany desired family or manufacturer. The hardware of processor 612 can bevirtualized using virtualization such as Virtual Machines (VM's) and/orcontainers. The processor 612 can implement aspects of example LEDcontroller 104B, example haptic device controller 106B, exampleintegrator 118, example comparator 120, example control logic 122,example integrator reset switch 126 and example delay timer 130.

The processor 612 of the illustrated example includes a local memory 613(e.g., a cache). The processor 612 of the illustrated example is incommunication with a main memory including a volatile memory 614 and anon-volatile memory 616 via a bus 618. The volatile memory 614 may beimplemented by Synchronous Dynamic Random Access Memory (SDRAM), DynamicRandom Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)and/or any other type of random access memory device. The non-volatilememory 616 may be implemented by flash memory and/or any other desiredtype of memory device. Access to the main memory 614, 616 is controlledby a memory controller.

The processor platform 600 of the illustrated example also includes aninterface circuit 620. The interface circuit 620 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 622 are connectedto the interface circuit 620. The input device(s) 622 permit(s) a userto enter data and commands into the processor 612. The input device(s)can be implemented by, for example, an audio sensor, a microphone, acamera (e.g. video camera), a keyboard, a button, a mouse, atouchscreen, a track-pad, a trackball, isopoint and/or a voicerecognition system.

One or more output devices 624 are also connected to the interfacecircuit 620 of the illustrated example. The output devices 624 can beimplemented, for example, by a haptic device, by a vibrator, by displaydevices (e.g., a head mounted display, head wearable display, wristwearable display, a light emitting diode (LED), an organic lightemitting diode (OLED), a liquid crystal display, a cathode ray tubedisplay (CRT), a touchscreen, a tactile output device, a light emittingdiode (LED), a printer and/or speakers). The interface circuit 620 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip or a graphics driver processor.

The interface circuit 620 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) via a network626 (e.g., an Ethernet connection, a digital subscriber line (DSL), atelephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 600 of the illustrated example also includes oneor more mass storage devices 628 for storing software and/or data.Examples of such mass storage devices 628 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, RAIDsystems, and digital versatile disk (DVD) drives.

The coded instructions 632 of FIGS. 3-5 may be stored in the massstorage device 628, in the volatile memory 614, in the non-volatilememory 616, and/or on a removable tangible computer readable storagemedium such as a CD or DVD.

Although FIG. 6 illustrates a processor based implementation of thecircuit of FIG. 1 , in some implementations digital or analog circuitryis used instead of a processor to implement the components of FIG. 1(e.g., the example LED controller 104B, example haptic device controller106B, example integrator 118, example comparator 120, example controllogic 122, example integrator reset switch 126 and example delay timer130.) In such implementation, the method of FIGS. 3-5 is instituted inthe circuitry and no program is needed to protect against thermal injuryand which may otherwise be caused by the overcurrent event.

Example 1 is a method of preventing thermal injury in a wearable device,the method comprising, sensing current from a battery, integrating asignal representative of the current from the battery using anintegrator to generate an integrator output, comparing the integratoroutput and an overcurrent threshold reference, generating an overcurrentindicator when the integrator output satisfies the overcurrent thresholdreference, and interrupting the current from the battery in response tothe overcurrent indicator to prevent the thermal injury.

Example 2 includes the method as in example 1, including delaying for acool down period after the interrupting of the current from the battery.

Example 3 includes the method as in example 1 including generating asave system state control signal in response to the overcurrentindicator.

Example 4 includes the method as in example 3 including delaying for asave system state period after generating the save system state controlsignal, and determining when the delaying for the save system stateperiod is finished, in which the interrupting of the current includesinterrupting the current after the save system state period is finished.

Example 5 includes the method as in one of examples 1-4 in which theinterrupting of the current includes generating an isolation switchcontrol signal in response to the overcurrent indicator.

Example 6 includes the method as in example 5 in which the interruptingof the current includes activating an isolation switch in response tothe isolation switch control signal.

Example 7 includes the method as in one of examples 1-4 includinggenerating an integrator reset control signal.

Example 8 includes the method as in one of examples 1-4 includingresetting an integrator in response to an integrator reset controlsignal.

Example 9 includes the method as in one of examples 1-4 includingresetting an isolation switch after interrupting the current from thebattery.

Example 10 is an apparatus comprising means to perform a method as inany preceding example.

Example 11 is machine-readable storage including machine-readableinstructions, when executed, to implement a method or realize anapparatus as in any preceding example.

Example 12 is a current controller to prevent injury from a batteryoperated wearable device comprising, a battery coupler to couple currentof a battery, a sense resistor in circuit with the battery coupler togenerate a voltage from the current of the battery, a current senseamplifier to sense the voltage of the sense resistor, an integrator incircuit with an output of the current sense amplifier to integrate theoutput of the current sense amplifier and to generate an integratoroutput, a comparator to compare an overcurrent threshold reference andthe integrator output to generate an overcurrent indicator, controllogic to generate an isolation switch control signal in response to theovercurrent indicator, and an isolation switch to interrupt delivery ofthe current of the battery to a load in response to the isolation switchcontrol signal to prevent burn injury to a wearer of the batteryoperated wearable device.

Example 13 includes the current controller as in example 12 in which theisolation switch includes a field effect transistor.

Example 14 includes the current controller as in example 12 in which thebattery operated wearable device is wrist wearable or head wearable.

Example 15 includes the current controller as in example 12 in which thecontrol logic is to generate the overcurrent threshold reference.

Example 16 includes the current controller as in one of examples 12-15in which the control logic is to generate an integrator reset controlsignal.

Example 17 includes the current controller as in example 16 in which theintegrator includes a reset switch to reset the integrator in responseto the integrator reset control signal.

Example 18 includes the current controller as in example 16 in which thecontrol logic is to generate a save system state control signal inresponse to the overcurrent indicator.

Example 19 is a head wearable system to avoid thermal head injury due toovercurrent, the system comprising, a battery, a sense resistor togenerate a voltage from a current of the battery, a current senseamplifier having inputs in circuit with the sense resistor to sense thevoltage of the sense resistor, an integrator in circuit with an outputof the current sense amplifier to integrate the output of the currentsense amplifier and to generate an integrator output, a reset switch toreset the integrator, a comparator to compare an overcurrent thresholdreference and the integrator output to generate an overcurrentindicator, and an isolation switch to interrupt the current of thebattery based on the overcurrent indicator to avoid the thermal headinjury.

Example 20 includes the head wearable system as in example 19 in whichthe isolation switch includes a field effect transistor.

Example 21 includes the head wearable system as in example 19 includinga light emitting diode in which the isolation switch is to interrupt anovercurrent through the light emitting diode.

Example 22 includes the head wearable system as in example 19 includinga haptic device in which the isolation switch is to interrupt anovercurrent through the haptic device.

Example 23 includes the head wearable system as in one of examples 19-22including control logic to generate a save system state control signalin response to the overcurrent indicator.

Example 24 includes the head wearable system as in example 23 in whichthe control logic includes a delay timer to delay for a save systemstate period after the control logic generates the save system statecontrol signal.

Example 25 includes the head wearable system as in example 24 in whichthe isolation switch is to interrupt the current of the battery afterthe delay timer delays for the save system state period.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. An apparatus to prevent injury from a wearabledevice, the apparatus comprising: a haptic device; an isolation switchconfigured to deliver power from a battery to the haptic device; anintegrator configured to integrate a signal based on a current from thebattery to the haptic device to generate an integrator output; a senseresistor in circuit with the battery and the isolation switch; a currentsense amplifier in circuit with the sense resistor and the integrator,the current sense amplifier configured to sense a voltage across thesense resistor; a comparator in circuit with the integrator, thecomparator configured to generate a comparator output based on acomparison of an overcurrent threshold reference and the integratoroutput; and control logic configured to control the isolation switchbased on the comparator output.
 2. The apparatus of claim 1, wherein thecontrol logic is further configured to control the isolation switchconfigured to interrupt delivery of the current from the battery to thehaptic device after the integrator output meets or exceeds theovercurrent threshold reference.
 3. The apparatus of claim 1, whereinthe haptic device is configured to vibrate.
 4. The apparatus of claim 1,wherein the control logic is further configured to generate anintegrator reset control signal to resume delivery of the current fromthe battery to the haptic device.
 5. The apparatus of claim 4, whereinthe integrator includes a reset switch configured to reset theintegrator after the control logic generates the integrator resetcontrol signal.
 6. The apparatus of claim 1, wherein the control logicis further configured to generate a save system state control signalafter the comparator generates the comparator output.
 7. The apparatusof claim 1, wherein the wearable device is a headset.
 8. A wearabledevice comprising: a haptic device; and control circuitry including: anintegrator configured to integrate a signal representative of currentfrom a battery to the haptic device to generate a first output; acomparator configured to generate a second output in response to thefirst output meeting or exceeding a threshold; and an isolation switch;and control logic configured to: activate the isolation switch inresponse to the second output, the activation of the isolation switchbeing configured to prevent a flow of the current from the battery tothe haptic device, the prevention of the flow of the current from thebattery to the haptic device to prevent thermal injury associated withthe wearable device.
 9. The wearable device of claim 8, wherein thecontrol logic is further configured to initiate a cool down period afterthe prevention of the flow of the current from the battery to the hapticdevice.
 10. The wearable device of claim 8, wherein the control logic isfurther configured to generate a save system state control signal inresponse to the second output.
 11. The wearable device of claim 10,wherein the control logic is further configured to initiate a savesystem state period after generating the save system state controlsignal, the prevention of the flow of the current to occur aftercompletion of the save system state period.
 12. The wearable device ofclaim 8, wherein the control logic is further configured to generate anisolation switch control signal in response to the second output. 13.The wearable device of claim 8, wherein the control logic is furtherconfigured to generate an integrator reset control signal to reset theintegrator.
 14. The wearable device of claim 8, further including areset switch configured to reset the integrator.
 15. An apparatus toprevent injury from a wearable device, the apparatus comprising: meansfor sensing current from a battery to a haptic device; means forintegrating a signal representative of the current to generate a firstoutput; means for generating a second output in response to the firstoutput meeting or exceeding a threshold; means for interrupting thecurrent from the battery to the haptic device in response to the secondoutput; and means for activating the means for interrupting in responseto the second output.
 16. The apparatus of claim 15, further includingmeans for initiating a cool down period after activation of the meansfor interrupting the current from the battery to the haptic device. 17.The apparatus of claim 15, wherein the means for generating is a firstmeans for generating, and the apparatus further includes second meansfor generating a save system state control signal in response to thesecond output.
 18. The apparatus of claim 17, wherein the second meansfor generating is configured to initiate a save system state periodafter generation of the save system state control signal, theinterrupting of the current to occur after a determination that the savesystem state period has expired.
 19. The apparatus of claim 15, furtherincluding means for generating an isolation switch control signal inresponse to the second output.
 20. The apparatus of claim 15, furtherincluding means for resetting the means for integrating.
 21. A method ofpreventing thermal injury from a wearable device, the method comprising:sensing current from a battery to a haptic device; integrating a signalrepresentative of the current to generate a first output; generating asecond output in response to the first output meeting or exceeding athreshold; and opening an isolation switch to interrupt the current fromthe battery to the haptic device in the response to the second output.22. The method of claim 21, further including initiating a cool downperiod after the interrupting of the current from the battery to thehaptic device.
 23. The method of claim 21, further including outputtinga save system state control signal in response to the second output. 24.The method of claim 23, further including initiating a save system stateperiod after the outputting of the save system state control signal, theinterrupting of the current to occur after determining that the savesystem state period is finished.
 25. The method of claim 21, furtherincluding generating an isolation switch control signal after thegenerating of the second output.